KR101433675B1 - The cold forging mold for manufacturing under driver brake piston - Google Patents

Abstract

A cold forging mold for manufacturing an underdrive brake piston according to the present invention includes a primary mold used to manufacture a semi-finished product by primarily cold-forging an initial material having a plate shape with a hole formed therein and a second mold used to manufacture a forging by secondarily cold forging the semi-finished product. The primary mold includes a primary punch and a primary die to form the semi-finished product by engaging the primary punch and die with each other in a state where the initial material is received in a primary molding space. The primary mold includes: a mounting part provided at one side of the primary die and making contact with the initial material to support the initial material so that the initial material is maintained at a predetermined height; an inclination part gradually narrowed under the mounting part to provide compressive force to the initial material when the initial material is forged; and a filling guide part for expanding a portion of the primary molding space adjacent to a bending part of the semi-finished product to reduce resistance against the movement of the material.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a cold forging mold for manufacturing an under drive brake piston,

The present invention relates to a cold forging die for manufacturing an underdrive brake piston and a method of manufacturing an underdrive brake piston using the same. More particularly, the present invention relates to a forging die having a sloped portion and a filler guide portion, The present invention relates to a cold forging die for manufacturing an underdrive brake piston and a method of manufacturing an underdrive brake piston using the same.

Under drive brake piston is a part used in an automatic transmission of a vehicle and constitutes an under drive for operating hydraulic pressure on a brake.

Such an underdrive brake piston is conventionally manufactured mainly by hot forging. However, since the hot forging requires heating the material to a high temperature, it takes a lot of time and cost, and it is difficult to satisfy the precise dimensions, so that the amount of material to be input is required to be larger than that of the simple and cold forging.

On the other hand, the cold forging requires no heating process, satisfies dimensional accuracy and surface roughness, and thus requires less amount of material to be input than hot forging, which is advantageous in accuracy and cost. Korean Patent No. 1019566 And is widely used in the manufacture of precision parts as in the prior art.

FIG. 1 is a sectional view of an underdrive brake piston manufactured by cutting a forged product, and FIG. 2 is a longitudinal sectional view taken along the line AA in FIG. 1. As shown in the drawing, the underdrive brake piston P is provided with a step portion 2, In the mold for forming the forged product, there is a problem that the flexibility of the material is insufficient to cause unfilled corner portions to be bent.

In order to solve the uncharging problem as described above, a press apparatus having a load capacity value of 2,500 tons or more must be used.

Further, there is no technology currently available for solving the above-mentioned uncharging problem other than a method of excessively increasing the load.

In addition, since the amount of deformation must be minimized in order to prevent uncharging or cracking of corners during cold forging, it is common practice to form the bending portion so as to gradually increase the bending amount.

Therefore, the number of processes increases and the amount of process inventories also increases, so that the manufacturing cost sharply increases, which is undesirable.

An object of the present invention is to solve the above-mentioned problems, and it is an object of the present invention to provide a method of manufacturing a forged metal mold, which comprises a forged metal mold having an inclined portion to guide a flow direction of a workpiece, The present invention is to provide a cold forging die for manufacturing an underdrive brake piston and a method of manufacturing an underdrive brake piston using the same.

A cold forging mold for manufacturing an underdrive brake piston according to the present invention comprises a primary die for forming a semi-finished product by first cold-forging an initial material having a hole formed therein, And a secondary mold for forming a forging product; Wherein the primary mold comprises a primary punch for forming a semi-finished product by curing the primary material while accommodating the initial material in a primary molding space, and a primary punch; Wherein the one end of the primary die is provided with a seating portion for supporting the initial material so as to maintain a constant height, a slope portion which is gradually narrowed from the bottom of the seating portion to provide a pressing force to the initial material during forging, And a filling guide part for reducing the flow resistance of the material by expanding a part of the primary molding space adjacent to the part.

And the filling guide portion is located at a position adjacent to the bent portion at which the initial stress is generated when the initial material is deformed by the primary forging.

Wherein the secondary die comprises a secondary punch for forming a forged product by cementing while the semi-finished products are accommodated in a secondary molding space, and a secondary punch; The second punch and the second punch include a plurality of parts, and the plurality of parts are spaced apart from each other to form a spacing part for reducing the material flow resistance during the secondary forging.

And the spacing portion is located at a position adjacent to the bent portion where tensile stress is generated when the semi-finished product is deformed by the secondary forging.

And the spacing distance of the spacing portion is proportional to the radius of curvature of the bent portion.

The secondary comprises an inner die and an outer die spaced apart from one another to form a spacing, wherein either the inner die or the outer die is movable independently.

Wherein the secondary punch comprises an inner punch and an outer punch which are spaced apart from each other to form a spacing portion, and wherein either the inner punch or the outer punch is movable independently, wherein the secondary punch comprises a cold forging die for manufacturing an underdrive brake piston .

The present invention relates to a method of manufacturing an underdrive brake piston using a cold forging mold for manufacturing an underdrive brake piston, the method comprising the steps of: placing a plate-shaped initial material having holes in its interior in a seating portion provided in a primary molding space of a primary mold A method of manufacturing a semi-finished product, comprising the steps of: placing a material in a mold, placing a first punch and a first die together to form a semi-finished product, A step of removing the forged product, a step of removing the forged product, a step of removing the forged product, a step of removing the forged product, and a step of finishing the underdrive brake piston to finish the underdrive brake piston The method comprising the steps of:

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The two-step blocking step is a step of molding the forgings by reducing the flow resistance at a portion where tensile stress is generated when the semi-finished product is pressurized.

In the present invention, an inclined portion is provided in the inside of the forging die so that the flow direction of the material is forcibly guided during forging.

In addition, a filling guide portion is provided at a portion where unfilling may occur, such as a bent portion, so that the material flows smoothly.

Therefore, since the forging moldability can be increased, the number of processes can be reduced, and the defect rate and the manufacturing cost can be remarkably reduced.

1 is an actual photograph of an underdrive brake piston manufactured by cutting a forged product and FIG.
2 is a cross-sectional view showing a change in shape of a material during molding using a cold forging mold for manufacturing an underdrive piston according to the present invention.
3 is a longitudinal sectional view showing a punch and a die structure of a primary die of a cold forging die for manufacturing an underdrive piston according to the present invention.
4 is a longitudinal sectional view showing a punch and a die structure of a secondary die of a cold forging die for manufacturing an underdrive piston according to the present invention.
5 is a process flow diagram illustrating a method of manufacturing an under-drive brake piston using a cold forging die for manufacturing an under-drive brake piston according to the present invention.
FIG. 6 is a longitudinal sectional view showing the internal state of the primary mold at the completion of the material seating step, which is one step in the method of manufacturing an underdrive brake piston using a cold forging mold for manufacturing an underdrive brake piston according to the present invention.
FIG. 7 is a longitudinal sectional view showing the inner state of the primary mold at the completion of the one-step blocking step in the method of manufacturing the underdrive brake piston using the cold forging mold for manufacturing an underdrive brake piston according to the present invention.
8 is a process analysis result showing the equivalent strain of FIG.
9 is a longitudinal sectional view showing the internal state of the secondary mold at the completion of the semi-finished product seating step, which is one step in the method of manufacturing the underdrive brake piston using the cold forging mold for manufacturing the under drive brake piston according to the present invention.
10 is a vertical cross-sectional view showing a state of a secondary mold during a two-stage stopping step in a method of manufacturing an under-drive brake piston using a cold forging mold for manufacturing an under-drive brake piston according to the present invention.
11 is a process analysis result showing the equivalent strain of Fig.
12 is a longitudinal sectional view showing the internal state of the secondary mold at the completion of the two-stage shut-off valve stage in the method of manufacturing the under-drive brake piston using the cold forging mold for manufacturing an under-drive brake piston according to the present invention.
13 is a process analysis result showing the equivalent strain of Fig.
FIG. 14 is a longitudinal sectional view showing the inner state of a secondary mold at the completion of the single step for taking out the forged product in the method of manufacturing the underdrive brake piston using the cold forging mold for manufacturing the under drive brake piston according to the present invention. FIG.

A state change of the initial material 10 in steps of the forging process using the cold forging mold for manufacturing an under drive brake piston according to the present invention will now be described with reference to FIG.

FIG. 2 is a cross-sectional view showing a change in shape of a material during molding using a cold forging mold for manufacturing an underdrive piston according to the present invention.

Prior to this, terms and words used in the present specification and claims should not be construed in a conventional and dictionary sense, and the inventor may appropriately define the concept of the term in order to describe its invention in the best possible way It should be construed as meaning and concept consistent with the technical idea of the present invention.

Therefore, the embodiments described in the present specification and the configurations shown in the drawings are merely preferred embodiments of the present invention, and are not intended to represent all of the technical ideas of the present invention. Therefore, various equivalents It should be understood that water and variations may be present.

As shown in the drawings, a cold forging die for cold rolling forging piston manufacturing according to the present invention (hereafter referred to as "cold forging die") is a method for cold forging a plate-like initial material 10, (20), and the semi-finished product (20) can be formed into a forged product (30) by a secondary cold forging process.

3) and a secondary mold (see 200 in FIG. 4) for manufacturing the forgings 30 are provided in the cold forging mold, .

The forged product 30 is finished with a finished product P through a post-process such as cutting. The cold forging mold is for producing a forged product 30 that is close to the shape of the finished product P.

The cold forging die is designed to increase the moldability of the bent part (F) formed on the semi-finished product (20) and the forged product (30). The detailed structure of the cold forging die will be described with reference to FIG.

3 is a longitudinal sectional view showing a punch and a die structure of a primary mold 100 of a cold forging mold for manufacturing an underdrive piston according to the present invention.

As shown in the drawing, the primary die 100 is configured to cold-mold the initial material 10 to form the semi-finished product 20, and includes a primary punch 120 and a primary die 140.

A primary molding space 142 is formed in the primary die 140 and a primary punch 120 is inserted into the primary molding space 142 to mold the semi-finished product 20.

The primary mold 100 is provided with a seating part 144 having a shape and an external size corresponding to the initial material 10. The seating part 144 is located on the uppermost side of the primary molding space 142 and allows the initial material 10 to be seated.

An inclined portion 146 is provided below the seating portion 144. The inclined portion 146 is configured to have an internal space narrower than the seating portion 144 and is configured to actually support the initial material 10 and to be gradually narrowed toward the lower side.

This is a configuration in which when the initial material 10 is pressed downward by the primary punch 120, the material flow direction of the initial material 10 is forced inward to generate a compressive force.

A filling guide 148 is provided on the inner bottom surface of the primary molding space 142. The filling guide portion 148 is configured to reduce the material flow resistance by recessing the portion adjacent to the bending portion F bent at the time of forming the initial blank 10 into the semi-finished product 20 to expand the space.

That is, the filler guide 148 may be configured such that the initial workpiece 10 is located at a position adjacent to the bent portion F where tensile stress is generated at the time of deformation by primary forging, thereby reducing the material flow resistance .

Accordingly, the primary molding space 142 does not correspond to the outer shape of the primary punch 120 by the inclined portion 146 and the filling guide portion 148, and has a slightly larger volume.

A detailed configuration of the secondary die 200 will be described with reference to FIG.

4 is a longitudinal sectional view showing a punch and die structure of a secondary die 200 of a cold forging die for manufacturing an underdrive piston according to the present invention.

As shown in the drawing, the secondary metal mold 200 is formed by placing the semi-finished product 20 inside and then cold forging to mold the forged product 30. The outer shape of the semi-finished product 20 is closer to the finished product P And the like.

That is, the secondary mold 200 includes the secondary punch 220 and the secondary die 240 by forming the forged product 30 by mating the semi-finished product 20 in a state of being accommodated in the secondary molding space 244 .

The second punch 220 and the second die 240 each include a plurality of parts, and the plurality of parts are spaced apart from each other to reduce the material flow resistance during the secondary forging.

Referring to FIG. 4, the secondary punch 220 and the secondary die 240 are formed of two parts, and the parts of the secondary punch 220 and the secondary die 240 are spaced apart from each other to form the spacing part 246.

The spacing part 246 is located at a position adjacent to the bent part F where tensile stress is generated at the time of deformation of the semi-finished product 20 by the secondary forging, ) Of the radius of curvature.

That is, referring to the shape of the semi-finished product 20 of FIG. 4, the radius of curvature of the bent portion at the upper side is smaller than that at the lower bent portion. Thus, a punch close to a small radius of curvature is provided with a narrow spacing 246, and a die close to a large radius of curvature is provided with a large spacing 246.

The secondary punch 220 includes an inner punch 227 and an outer punch 228. The outer punch 228 includes a first punch 220 and a second punch 220. The second punch 220 includes an inner punch 227 and an outer punch 228. [ The inner punch 227 and the outer punch 228 are configured to be capable of independent linear reciprocating motion in the up / down direction. In the secondary forging process, And the outer punch 228 is configured to sequentially press the outer side of the semi-finished product 20 as shown in Fig. 12 after the pressing action of the inner punch 227. As shown in Fig.

On the other hand, the secondary die 240 is configured to be able to take out the molded forgings 30. That is, the secondary die 240 includes an inner die 247 and an outer die 248, and a spacing portion 246 is formed between the inner die 247 and the outer die 248, Either the inner die 247 and the outer die 248 are independently movable.

A method of manufacturing an under-drive brake piston using the cold forging die will be described with reference to FIG.

5 is a flow chart showing a process for manufacturing an under-drive brake piston using a cold forging mold for manufacturing an under-drive brake piston according to the present invention.

As shown in the figure, the forged product 30 includes a plate-like initial material 10 having holes 12 formed therein and a seating part 144 (see FIG. 1) provided in the primary molding space 142 of the primary mold 100 (S100) for forming a semi-finished product (20) by squeezing the primary punch (120) and the primary die (140) A semi-finished product placing step (S400) for placing the semi-finished product (20) inside the secondary mold (200), a second punch (220) A forging step (S500) for forming a forged product (30) by curing the forged product (240), and a forging step (S600) for taking out the forged product (30) It is possible to further complete the post-machining step (S700) for machining the outer surface to complete the underdrive brake piston which is the finished product (P).

The above manufacturing method will be described in order with reference to Figs. 6 to 14. Fig.

6, the initial material 10 includes an inclined portion (not shown) formed at an oblique lower portion of the seating portion 144, 146 to limit downward movement.

Thereafter, the first punch 120 is transferred in the downward direction to perform one blocking step (S200).

The first blocking step S200 is a process of molding the initial material 10 into a semi-finished product 20 by molding the primary punch 120 and the secondary punch 220 together, The portion where the tensile stress is generated at the time of deformation by the semi-finished product 20 is formed by the filling guide portion 148 formed by extending a part of the primary molding space 142, The flow resistance is lowered and the frictional resistance generated between the initial material 10 and the primary die 140 is reduced, so that the moldability can be increased as shown in FIG.

That is, FIG. 8 shows the results of the process analysis showing the equivalent strain of FIG. 7, showing that the semi-finished product 20 is formed by the action of the inclined portion 146 and the filler- As shown in FIG.

After completion of the first blocking step S200, a semi-finished product take-out step S300 for taking out the semi-finished product 20 in the primary mold 100 is performed, and the semi-finished product 20 taken out is placed in the semi-finished product seating step S400 And then the second blocking step S500 is performed.

12, the second punch 220 is moved in a state where the semi-finished product 20 is seated on the upper surface of the inner die 247 as shown in FIG. 9 to pressurize the semi-finished product 20, The forging 30 can be formed.

During the process of forming the semi-finished product 20 into the forged product 30, the spacing portion 246 reduces the flow resistance at a portion where tensile stress is generated, thereby improving the formability of the forged product 30. As described above, The spacing portions 246 are formed to have different sizes from each other in the second punch 220 and the second die 240, so that the magnitude of the flow resistance can be controlled.

As shown in FIG. 10, the inner punch 227 and the inner die 247 of the secondary punch 200 are arranged in the order of the inner punch 227 and the outer punch 228, The semi-finished product 20 is pressed first.

At this time, the outer side of the inner punch 227 guides the bent part of the semi-finished product 20 to the spacing part 246 to induce filling of the material, and it can be confirmed that the amount of friction is small as shown in FIG.

After the pressing action of the inner punch 227 and the inner die 247, the outer punch 228 and the outer die 248 come close to each other to complete the forging 30 as shown in FIG.

At this time, as shown in FIG. 13, the flow of the material is guided by the spacing portion 246 of the stepped upper / lower end portion of the semi-finished product 20 so that filling can be smoothly performed.

After the two-step blocking step (S500), the forging step (S600) is performed. The forging step (S600) is a process for moving the inner die (247) upward to lift the forged product (30) to the outside of the secondary die (200) as shown in FIG.

When the forging step S600 is completed, molding of the forgings 30 is completed. If the post-processing step S700 is further performed, the finished product P shown in Fig. 1 can be completed.

The scope of the present invention is not limited to the above-described embodiments, and many other modifications based on the present invention will be possible to those skilled in the art within the scope of the present invention.

10. Initial material 12. Hall
20. Semifinished products 30. Forgings
100. Primary mold 120. Primary punch
140. 1 Chadai 142. Primary molding space
144. Seat part 146. Inclined part
148. Filling guide section 200. Secondary mold
220. Second punch 227. Inner punch
228. Outer punch 240. 2 Chadai
244. Second molding space 246. Separation part
247. Inner die 248. Outer die
F. Bending section P. Finished
S100. Material seating step S200. 1 Blocking phase
S300. Semifinished product take-out step S400. Semifinished product placement stage
S500. 2 Blocking step S600. Forging step
S700. Post-processing step

Claims (10)

A primary mold for forming a semi-finished product by first cold-forging an initial material having a hole in the inner perforated hole, and a secondary mold for forming a forged product by secondary cold-forging the semi-finished product ;
Wherein the primary mold has,
A primary punch for forming a semi-finished product in a state where the initial material is accommodated in a primary molding space, and a primary punch;
On one side of the primary die,
A seating part for supporting the initial material so as to maintain a constant height,
An inclined portion which becomes narrower at a lower portion of the seat portion and provides a compressive force to the initial material during forging;
And a filling guide portion for expanding a part of the primary molding space adjacent to the bending portion of the semi-finished product to reduce the flow resistance of the workpiece.
delete The method according to claim 1,
A secondary punch for forming a forging product by cramping the semi-finished product in a state of being accommodated in a secondary molding space, and a secondary punch;
The secondary punch and the secondary punch comprise a plurality of parts, respectively,
Wherein the plurality of parts are spaced apart from each other to form a spacing part for reducing the material flow resistance during the secondary forging molding.
delete 4. The cold forging mold for manufacturing an underdrive brake piston according to claim 3, wherein a spacing distance of the spacing portion is proportional to a radius of curvature of the bent portion.
6. The method of claim 5,
And an inner die and an outer die which are spaced apart from each other to form a spacing portion,
Wherein one of the inner die and the outer die is independently movable. ≪ RTI ID = 0.0 > 11. < / RTI >
The apparatus of claim 5, wherein the secondary punch comprises:
And an inner punch and an outer punch which are spaced apart from each other to form a spacing portion,
Wherein one of the inner punch and the outer punch is independently movable. ≪ RTI ID = 0.0 > 11. < / RTI >
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